Power-operated crutch



1968 w. T. CARPENTER POWER-OPERATED CRUTCH Filed Nov. 29, 1967 .4 Viz W.T. CARPENTER "-2 INVENTOR.

BY M,

FIG. 3

ATTORNEYS United States Patent 3,416,546 POWER-OPERATED CRUTCH WilliamT. Carpenter, Houston, Tex. (Rte. 1, Box 102 A, Ragley, La. 10657) FiledNov. 29, 1967, Ser. No. 686,509 20 Claims. (Cl. 135-49) ABSTRACT OF THEDISCLOSURE This application discloses a crutch of the type used byhandicapped persons, the crutch being expandable under power whereby theuser may raise himself from sitting to a standing position. The crutchincludes upper and lower telescoping sections which provide a hydraulicpiston and cylinder arrangement, with extension of the crutch beingprovided by forcing hydraulic fluid under pressure into the cylinder. Ahydraulic reservoir having a floating piston therein is used forsupplying fluid to the cylinder, the power for moving the floatingpiston being compressed gas. A gas chamber located in the crutch assembly stores high pressure gas, and the reservoir may be charged with asmall volume of the high pressure gas through a valve arrangement as thefirst step in the operating cycle. Secondly, hydraulic fluid is admittedinto the cylinder by another valve to extend the telescoping sections.To lower or retract the crutch, the user first vents the gas in thereservoir by a valve, then opens another valve to allow the hydraulicfluid to cycle back into the reservoir.

Power-operated crutches have been devised which are used by handicappedpersons as an assist in raising themselves from a sitting position to astanding position, or lowering themselves to a sitting position.Crutches of this type are shown in U.S. Patents 3,157,188 and 3,157,189issued Nov. 17, 1964 to George R. Farnham, these crutches employingelectrical or hydraulic motive power systems which are operated by thehandicapped persons using fingertip controls. While the crutchesaccording to the Farnham patents have been acclaimed as providing amajor advance in the art, the difficulty of fabricating miniature,lightweight components such as electrical motors as used in thesedevices has markedly restricted their utility.

The potential improvement in mobility and freedom of action for ahandicapped person provided by a poweroperated crutch is surprisinglygreat. Invalids, otherwise confined to the bed or wheelchair unlessaided by another person in raising themselves to an upright condition sothat conventional crutches may be used, are able to be much more active,independent and self-sufficient. However, the crutches previouslyproposed, while potentially quite eifective, have required especiallymade electro-mechanical components which resulted in the crutches beingproduced only on a very limited basis, one at a time, with the resultanthigh costs rendering the devices virtually unavailable to thehandicapped, these being persons inherently of limited resources.

It is the primary feature of the power operated crutch of this inventionthat it may be readily manufactured using simple, rugged and readilyavailable parts. Another feature is the simplicity, positive operation,and maintenance-free construction of the air-gas motive power systemwhich is utilized. Other features include costs advantages and facilityof manufacture which reduce the time required in obtaining parts andcompleting the fabrication cycle.

In accordance with this invention, a power-operated crutch is providedusing a pair of telescoping, tubular sections which function as thepiston and cylinder of a hydraulic arrangement. An auxiliary hydraulicreservoir 3,416,546 lc Patented Dec. 17, 1968 having a floating pistonis used to force hydraulic oil into the cylinder or receive oil from thecylinder. A high pressure gas supply located within the crutch assemblyis connected to the reservoir on one side of the floating piston by avalve which permits admitting a charge of high pressure gas to thereservoir. Another valve, manually operated by a fingertip controladjacent the handle of the crutch gripped by the user, permits fluid tobe admitted into the cylinder from the reservoir to raise the crutch.The crutch is lowered by venting the reservoir, again by a fingertipcontrol, and then opening the valve to allow fluid to re-enter thereservoir from the cylinder. All of these components are located withina small, lightweight crutch assembly which is of rugged and trouble-freeconstruction.

Novel features which are believed characteristic of the invention areset forth in the appended claims. The invention itself, however, as wellas other features and advantages thereof, may best be understood byreference to the following detailed description of a particularembodiment, when read in conjunction with the accompanying drawing,wherein:

FIGURE 1 is a pictorial view of a power-operated extendable crutchaccording to one embodiment of the invention;

FIGURE 2 is a detail view, partly in section and partly in schematicform, of the motive power system and control arrangement for the crutchassembly of FIGURE 1; and

FIGURE 3 is a view similar to FIGURE 2 in a different operating stage.

The drawings are considered a part of this specification and areincorporated herein. It is noted that like parts appearing in severalviews of the drawing bear like reference numerals.

With reference to FIGURE 1, a power-operated crutch according to anembodiment of the invention is shown externally. This device consists ofan elongated crutch body 10 which may include an upper telescopingsection having an outer tubular portion 11 and an inner tubular portion12, the tube 12 telescoping into the tube 11 to adjust the height of theupper part of the crutch. A knurled collar 13 fitted on a threaded andslotted lower portion of the tube 11 may be turned to a bold position ora release position as is conventional. In like manner, the lower part ofthe crutch may be adjusted to fit the users height as it comprises anouter tube 14 and an inner tube 15 which are secured to one another by areleasable knurled collar 16. Connected to the upper end of the tube 11is an armpit rest 17, while a resilient foot member 18 is fitted overthe lower end of the tube 15 in conventional manner. Centrally locatedalong the crutch body 10 is a housing 19 containing the air-hydraulicpower mechanism, with a handle or hand-grip 20 being secured to theupper part of the housing. Push-button type control valves 21 arepositioned on the top of the housing 19 adjacent the handle 20 to beconveniently operated by the thumb of the user while he is gripping thehandle. It is noted that this power-operated crutch is a convenientself-contained unit which is rather small and lightweight. A left-handcrutch is illustrated, it being understood that a similar crutch havingthe control buttons 21 properly positioned would provide the right-handunit of a pair. In operation, the user would first adjust thetelescoping sections 11 and 12 by means of the collar 13 so that thedistance between the armpit rest 17 and the handle 20 correspondscomfortably to the length of his arms. In like manner, the telescopingtubes 14 and 15 would be adjusted by the collar 16 so that the overalllength of the crutch body 10 from the armpit rest 17 to the foot 18,with the power operated mechanism in the extended condition as will bedescribed, would support the user comfortably in a standing positionaccording to his height. Now, by manipulating the controls 21. for eachcrutch with his thumb in the manner set forth below, the user may causethe section 14 to telescope within the section 12 through the housing 19to lower himself in a controlled manner to a sitting position; likewise,once in a sitting position he may cause the sections 12 and 14 to extendwith respect to one another under power to raise himself to a standingposition. The retraction and expansion operations are controlled inspeed, but yet comfortably rapid, so that the user is not unduly upsetby use of the crutch, while at the same time the operation is nottediously slow. The power mechanism will now be described in detail.

With reference now to FIGURE 2, there is illustrated an enlarged detailview of the operating mechanism, artly in schematic form, as principallylocated within the housing 19. It is noted that the lower tube 14 whichtelescopes within the upper tube 12 is of appreciably smaller diameter,and this tube is sealed on its upper end by a cap 22 so that the tube 14acts as a piston. The cap 22 is slightly larger than the diameter of thetube 14 so that when the telescoping sections 12 and 14 are in theextended condition (FIGURE 2 illustrates these elements in the retractedor telescoped condition) the cap 22 will engage the upper edge of asleeve or gland 23 and act as a stop. The sleeve 23 is rigidly securedand sealed to the inner diameter of the tube 12, and the tube 14 slideswithin the sleeve 23, an O-ring seal 24 preventing loss of hydraulicfluid which is contained within a chamber 25 between the smaller tube 14and the larger tube 12. The upper end of the tube 12 is sealed by a cap26, and the chamber 25 is filled with hydraulic oil, the piston or tube14 being driven to an extended position for the crutch by forcing fluidinto the chamber 25 under pressure, or the crutch being allowed toretract by venting fluid from the chamber 25 through an inlet port 27 aswill be described. The O-ring seal 24 prevents loss of hydraulic oilaround the tube 14, but in order to avoid wetting of the exposed portionof the tube 14 with hydraulic oil when the crutch is run up to itsextended position, a felt wiper 28 of annular configuration ispositioned in a collar 29 which is fitted onto the lower end of thesleeve 23 by a thread arrangement. The collar 29 is removable to permitreplacement of the wiper 28 when it becomes saturated with hydraulicoil.

The gas-hydraulic power mechanism for operating the telescopingpiston-cylinder arrangement of FIGURE 2 will now be described. It isnoted that the inlet 27 to the chamber 25 is located within a manifoldblock 30 which surrounds the tube 12 and provides a rigid support forthe handle 20, as well as containing various ports, passages, and valvesfor the control mechanism which is schematically represented. Thismanifold block may be a solid aluminum member suitably shaped and bored.

Located within the housing 19 is a large gas and oil reservoir 31 whichis connected at the lower end by a conduit 32, through an orifice 33 anda push-button operated valve 34, to the inlet port 27. A floating pistonseparates the hydraulic oil in the lower portion of the chamber 31 frompressurized gas in the upper end of the reservoir. When the floatingpiston 35 is pushed downward by gas pressure, hydraulic oil flows fromthe lower end of the reservoir through the conduit 32, if the valve 34is opened, and into the port 27, thus forcing the tube or piston 14downward. The rate at which fluid can pass through the conduit 32 intothe port 27 is determined by the orifice 33 which is dimensioned tolimit the maximum rate of operation of the crutch to avoid injury to orunbalance of the user. The valve 34 is a metering type valve biased inthe closed position by a spring and opened by a push-button as will beexplained.

Compressed gas is admitted to the upper end of the reservoir 31, abovethe floating piston 35, from a pressure cylinder 36 through conduit 37,a valve 38, and a conduit 39 which leads into a small chamber-40. Thechamber 40 is defined in the upper end of the reservoir by a sleeve 41which, when the piston 35 is in its uppermost position, provides achamber to receive a charge of compressed gas. The valve 38 is normallyclosed, and the cylinder 36 contains a gas such as CO at perhaps 900p.s.i. or other convenient pressure. When the valve 38 is openedbriefly, the chamber 40 will be charged to the cylinder pressure, butthe floating piston 35 will not move so long as the valve 34 is closed.The cylinder 36 usually would contain mostly liquid CO and this cylinderincludes an external fitting 42 of conventional type which is exposed atthe outer face of the housing 19 to permit recharging of the cylinder36. The chamber 40 may be vented to atmosphere through a conduit 43 anda normally-closed valve 44 which is operated by a push-button. A muffier45 comprising a small chamber with bafiles would be used to avoid noisewhen the gas is vented.

The fingertip control arrangement 21 employs three push-buttons 46, 47,and 48, as seen in FIGURE 2, for operating the valves 38, 34 and 44,respectively. These push-buttons are operated by the thumb of the userfor each hand to raise and lower the power-operated crutches. Each ofthe valves 38, 34 and 44 is normally closed, and is opened by depressingthe corresponding push-button. The operation will be explained in detailbelow.

While the particular dimensions employed in this embodiment of theinvention are not critical, it will be an aid in understanding theinvention to consider the relative sizes of the variou components. Thestroke of the piston defined by the upper end of the tube 14 is about18", this being the operating or lifting range of the crutch. Thediameter of the chamber 25 is about 1", whereas the effective diameterof the piston 14 is about so the volume of hydraulic oil needed to beadded to the chamber 25 to drive the piston from fully retracted tofully extended positions is about 5 in. Accordingly, the reservoir 31must contain at least this quantity of oil, indeed the chamber 31preferably contains about 7 in. of hydraulic oil to account for lossesdue to slight leakage over several months of operating time. Thereservoir 31 is about 1 /2" diameter and 6" long to fit convenientlywithin the housing 19. For operation at about 900 p.s.i. pressure in thecylinder 36, the chamber 40 should be about diameter by 1" length toreceive a charge of compressed gas which is sufficient to drive thefloating piston 35 the length of the reservoir 31, against the weight ofa 240 lb. person supported by two crutches. With these ratios, and usinga cylinder 36 of about 2 /2" by 8" or 40 in. there would be enoughpressurized CO for about strokes. It has been found that the averageperson used the power-operated feature of the crutch about thirty timesper day, and so one charge of the CO cylinder 36 would last for aboutthree days on average. In this example, the sleeve or gland 23 is about5" in length, and this member may be composed of honed cast iron toprovide the necessary tolerance. The piston or tube 14 fitting withinthis gland could be formed of cold drawn steel seamless tubing which isground to size, chromed and polished, or perhaps stainless steel whichis ground and polished, the tolerance between the OD of the piston 14and the ID of the gland 23 preferably being about 0.002". These specificdimensions of course are merely illustrative.

In operation of the gas-hydraulic powered crutch as described above, itwill be first assumed that the crutch is in condition of FIGURE 2, i.e.,in the retracted condition as when the user is seated. To raise himselfto the standing position, the user would lean forward and place the twocrutches under his arms and grasp the handles 20, then with his thumb hewould press the push-button 46 of the control unit 21 for each crutch.This would serve to open the valve 38 and admit a charge of gas at 900p.s.i. into the chamber 40. The push-button 46 would be released so thevalve 38 would close, and the mechanism would remain in this condition,the chamber 40 pressurized, until the push-button 47 is depressed. Whenthe latter button is operated, the valve 34 would open to a degreedependent upon how far the button 47 is pushed. This permits hydraulicoil to pass out of the reservoir 31 as the floating piston 35 is drivendown by gas pressure, and the oil will pass through the orifice 33 whichdetermines the maximum rate and into the chamber through the inlet 27.This drives the piston 14 downward, and this condition will continueuntil suflicient fluid has moved from the reservoir 31 to the chamber 25to drive the piston 14 to the position seen in FIGURE 3, the cap 22ultimately contacting the upper rim of the gland 23, and the floatingpiston moving to near the bottom of the reservoir 31. The button 47would be held down to hold the valve 34 open during the time required tomove the piston 14 all the way to the extended position of FIGURE 3,this requiring perhaps several seconds with the valve 34 all the wayopen, or a longer period if the valve is not opened fully. Now the valve34 will be closed by releasing the thumb pressure on the button 47, andthe crutch Will remain in this extended position indefinitely since thehydraulic fluid cannot escape. To lower the crutch, first the valve 44would be opened by depressing the button 48 to permit the gas in the topof the reservoir 31 to be vented to atmosphere thnough the mufiler 45.Assuming no gas leakage from the chamber 31 while the crutch was in theextended condition, the pressure with in the reservoir 31 will still beperhaps 300 p.s.i. (assuming that about /3 in. at 900 p.s.i. hasexpanded to about 5 /2 in. in the reservoir 31). Except for leakage,this pressure will be maintained, and the crutch could not retract untilthe pressure is vented. After the pressure is vented and the button 48released to close the valve 44, the reservoir 31 will again be sealed.Now the valve 34 is again opened to permit flow of hydraulic oil in theother direction, by pressing the button 47, and so the weight of theuser bearing down on the crutches will cause the piston 14 to be forcedback into the chamber 25 toward the condition illustrated in FIGURE 2,this filling up the reservoir 31 and forcing the floating piston 35 backup to the top. This will compress the gas trapped within the chamber 40,building up a pressure of perhaps 20 p.s.i. This gas pressure ismaintained so that when the cycle is repeated a small amount of the gaspressure is conserved since the pressure in the chamber need not bebrought up from zero. It is thus seen that either raising or loweringthe crutch is a two-step process. For lowering, first the button 48 isdepressed, then it is released and the button 47 is depressed. Likewise,for raising, first the button 46, then the push-button 47 is operated.

In the construction of the power-operated crutch of the invention, itmay be noted that the manifold block 30 would be a major structuralmember consisting of an aluminum block perhaps 1 /2" thick and of a sizeequal to that of the top of the housing 19. This block would be suitablydrilled and shaped to provide the various passageways and positions forthe valves 34, 38 and 44 along with the push-buttons 46-48 which arespring biased in the upward position. In addition, the block wouldprovide a firm support for the handle 20.

It is noted that the armpit rest 17 illustrated is of the non-paddedtype to reduce the bulkiness of the unit, and so to overcome theadditional discomfort which might occur due to the added force appliedduring the raising operation, the rests 17 are especially shaped. Theshaping includes a recess 49 in the front upper end of each rest to aidin fitting the contour of the body and relieving nerve pressure orrestriction of circulation in the arm of the user.

It is further noted that the cap 26 in the upper end of the tube 12includes a bleeder fitting 50 which is used to bleed air out of thehydraulic cylinder to avoid spongy operation. Slight amounts of air orgas may leak into the hydraulic system over long periods of time, butthis is easily remedied by the bleeder fitting.

The purpose of the floating piston 35 in the assembly described above isto separate the pneumatic and hydraulic portions of the system. Thisfunction may be accomplished by the use of a hydraulic accumulator ofthe type having an expandable bladder to receive the oil within achamber, the chamber containing the gas around the exterior of thebladder so that by changing the gas pressure the oil may be forced outinto the driving cylinder or allowed to drain back into the bladder.However, the float ing piston arrangement is preferred from a cost, sizeand reliability standpoint. In like manner, this separation functioncould be dispensed with and the assembly would operate in the samemanner, but there may be a problem of air getting into the oil cylinder25, producing a spongy effect, or oil escaping through the muflier 45where the air is vented, this being annoying to the user. An air-oilseparator could be used at the rnuifler, but this would be needlesslybulky and expensive. Thus, the floating piston feature is mostpreferable.

In place of the charging chamber 40, a pressure regulator could be usedin the output line 37 from the air cylinder 36 to provide a constant lowpressure to the reservoir, but this would require a different operatingcycle in that the valve 46 would have to be open during the entire timethe floating piston moved downward, and also the pressure regulator isbulky and expensive.

As a safety feature, the orifice 33 may be located at the tip of theinlet 27, just at the point where it enters the chamber 25, so that theoil cannot escape faster than a certain valve even though the valve orline might fail. Thus, the crutch would not collapse, but instead wouldcontract fairly slowly.

While the invention has been described with reference to a particularembodiment, this description is not meant to be construed in a limitingsense. Various modifications of the disclosed embodiment, as well asother embodi ments of the invention, maybe obvious to persons skilled inthe art upon reference to this description. It is therefore contemplatedthat the appended claims will cover any such modifications orembodiments as fall within the true scope of the invention.

What is claimed is:

1. A power-operated crutch of the type including an elongated crutchbody assembly having a pair of elongated telescoping sections, and acrutch handle located at an intermediate point along the crutch bodyassembly:

one of the telescoping sections fitting coaxially within,

and being substantially smaller than, the other of the telescopingsections to provide a hydraulic piston and cylinder arrangement,

a hydraulic reservoir,

means for introducing compressed gas into the hydraulic reservoir,

means including a manually-operated valve for connecting the hydraulicreservoir to the hydraulic cylinder between the telescoping sections.

2. A power-operated crutch according to claim 1 wherein the size of theupper end of the lower one of the telescoping sections is substantiallyless than the interior dimension of the lower end of the .upper one ofthe telescoping sections, whereby suflicient interior space is providedbetween the sections to permit introduction of hydraulic fluid in thevicinity of said handle at said intermediate point.

3. A power-operated crutch according to claim 2 wherein annular wipermeans is provided at the lower end of the upper telescoping section toprevent exposure of fluid-wetted portions of said lower telescopingmember upon extension of the crutch assembly.

4. A power-operated extenda'ble crutch according to claim 3 wherein acylindrical sleeve secured to the interior of the lower end of the uppertelescoping section surrounds the upper end of the lower telescopingsection,

and a stop member located on the upper tip of the lower telescopingsection engages said sleeve upon maximum extension of the crutchassembly.

5. A power-operated crutch according to claim 1 wherein the effectiveoperating displacement provided by movement of gas into said hydraulicreservoir is slightly greater than the maximum eflective displacement ofsaid piston and cylinder arrangement provided by the telescopingsections.

6. A power-operetad crutch according to claim 1 wherein an orifice isinterposed between said reservoir and said hydraulic cylinder torestrict the maximum rate of extension of the crutch assembly, and saidmanuallyoperated valve for admitting hydraulic fluid into said pistonand cylinder arrangement may be variably positioned to control the rateof extension of the crutch assembly.

7. A power-operated crutch according to claim 1 wherein an orifice isinterposed between said other end of the reservoir and said hydrauliccylinder to restrict the maximum rate of extension of the crutchassembly, and said manually-operated valve for admitting hydraulic fluidinto said piston and cylinder arrangement may the variably positioned tocontrol the rate of extension of the crutch assembly.

8. A power-operated extendable crutch according to claim 1 wherein a gascharging chamber is provided at one end of said hydraulic reservoir, andmanually-operated valve means are provided for charging said chamberfrom a supply of pressurized gas.

9. A power-operated crutch according to claim 8 wherein furthermanually-operated valve means connect said charging chamber toatmosphere whereby said one end of the reservoir may be vented.

10. A power-operated crutch according to claim 8 wherein said chamber isvented to atmosphere through a mufiier.

11. A power-operated crutch of the type including an elongated crutchbody assembly having a pair of elongated telescoping sections, a powersystem housing and a crutch handle located at an intermediate pointalong the crutch body assembly, and an armpit rest at the upper end ofthe crutch body assembly, said crutch comprising:

a hydraulic piston and cylinder arrangement provided at the telescopingportion of the sections,

a hydraulic reservoir having a floating piston therein,

means for introducing a charge of compressed gas into the hydraulicreservoir on one side of the floating piston,

a valve for connecting the hydraulic reservoir at the other side of saidfloating piston to the hydraulic cylinder to selectively admit or venthydraulic liquid to or from said piston and cylinder arrangement.

12. A power-operated crutch according to claim 11 wherein thetelescoping sections fit coaxially to provide the piston and cylinder,the size of the upper end of the lower one of the telescoping sectionsis substantially less than the interior dimension of the lower end ofthe upper one of the telescoping sections, whereby suflicient interiorspace is provided between the sections to permit introduction ofhydraulic fluid in the vicinity of said power system housing at saidintermediate point of the crutch body assembly.

13. A power-operated crutch according to claim 12 wherein the effectiveoperating displacement provided by movement of said floating pistonWithin said hydraulic reservoir is slightly greater than the maximumeflective displacement of said piston and cylinder arrangement providedby the telescoping sections.

14. A power-operated extendable crutch according to claim 13 wherein agas charging chamber is provided at said one side of said floatingpiston in said hydraulic reservoir, and manually-operated valve meansare provided for charging said chamber from a supply of pressurized gas.

15. A power-operated crutch according to claim 14 wherein the valveconnecting the hydraulic reservoir to the hydraulic cylinder is manuallyoperated by a push-button located on said housing closely adjacent saidhandle and closely adjacent a push-button for actuating said manuallyoperated valve means for charging said chamber.

16. A power-operated crutch according to claim 15 wherein furthermanually-operated valve means connect said charging chamber toatmosphere whereby said one end of the reservoir may be vented, suchfurther valve means being actuated by a push-button located closelyadjacent said other push-button.

17. A power-operated crutch according to claim 16 wherein the pushbuttons are located on the top of said housing within convenient reachof the thumb of the user gripping said handle.

18. A power-operated crutch according to claim 17 wherein all of saidvalves and valve means are spring biased to a normally closed position;and wherein a twostep procedure of cycling the valves is required forextending or retracting the crutch assembly.

19. A power-operated crutch according to claim 13 wherein annular wipermeans is provided at the lower end of the upper telescoping section toprevent exposure of fluid-wetted portions of said lower telescopingmember upon extension of the crutch assembly.

20. A power-operated crutch according to claim 13 wherein a cylindricalsleeve secured to the interior of the lower end of the upper telescopingsection surrounds the upper end of the lower telescoping section, and astop member located on the upper tip of the lower telescoping sectionengages said sleeve upon maximum extension of the crutch assembly.

References Cited UNITED STATES PATENTS 710,074 9/1902 Pratt 62 2,426,5949/1947 Buell et a1. 135-61 2,479,667 8/1949 Shellhouse et al. 13561 X3,157,188 11/1964 Farnham 1355O 3,157,189 11/1964 Farnham 135-503,158,851 11/1964 Ruthven 13547 X PETER M. CAUN, Primary Examiner.

U.S. Cl. X.R. 135--50

